Technical Field
Aspects of the present disclosure relate to a data transfer device and a data transfer method, and a non-transitory recording medium storing program code for executing a data transfer method.
Related Art
A high-speed serial interface is often used to improve image data transfer capability of image forming apparatuses. As a typical high-speed serial interface, there is Peripheral Component Interconnect Express, or PCI Express, which is a serial computer expansion bus standard. Data transfer in PCI Express is performed in packet units, and a mechanism that uses a plurality of data flow buffers sharing a common link called a virtual channel (VC) is used to control the packets. Each virtual channel has resources such as independent buffers and is controlled independently in the link. A traffic class (TC) is associated with the virtual channel and priority can be assigned to the virtual channels depending on the traffic class.
Depending on the standard, up to eight virtual channels can be used. Of the eight virtual channels, only a single virtual channel is required and the other channels are optional. VC0 and TC0 are fixedly associated as a specification of PCI Express. A technique is known that allocates different virtual channels for each traffic class to devices such as an LSI and establishes priorities for data transfer using a mechanism for associating VC with TC.